The present invention relates to method and apparatus for converting a combustion heat of a fuel to infrared rays and for heating a human body or various kinds of objects.
In this specification, it is assumed that the infrared rays include far infrared rays whose wavelengths are 0.1 mm or less and, preferably 1 to 30 micron.
In recent years, it has been known that the light in the region called far infrared rays of long wavelengths in the infrared rays is the light which can be easily absorbed into the water, organic substance, human body, or the like.
The present invention intends to obtain method and apparatus in which a combustion heat of a fuel is converted to far infrared rays with a high heat efficiency and at the same time hot water, hot air, or the like are generated, and thereby efficiently heating a human body or objects.
As a conventional far infrared rays radiating apparatus using a combustion heat as a heat source, there has been widely known an apparatus in which a fuel is combusted in a tubular combustion chamber, the combustion gas in the downstream of the tubular combustion chamber is led into the radiating pipe and allowed to flow therethrough, and the far infrared rays are radiated from the outer surface of the tubular combustion chamber and the outer surface of the radiating pipe.
The apparatus of this system has the following problems. In the ordinary combusting method, a temperature of combustion flame reaches a high temperature of 1500.degree. to 2000.degree. C. or more. Therefore in particular, if the water cooling or forced air cooling is not performed, the surface temperature of the combustion pipe rises too high to about 800.degree. to 1500.degree. C., so that it is heated in red and burned out. Even if it is burned out, since the temperature is too high, the near infrared rays of short wavelength are mainly irradiated. Thus, such an apparatus is improper as a far infrared rays radiating apparatus.